Tube expanding and smoothing mills



June 17 1924. I 1,498,130

' R. C. STlEFEL TUBE EXPANDING AND SMOOTHING MILL Filed Anril l6 1923 Expanding Taten'ted' Jane 117, i924.

LEE (7. STIEFE, 0F MLWOQD GITY, PENNSYLTTANIA.

TUBE EXPANDING- AND S31E00 5;. ll. MHILS.

Application filed. April 16, 1923. Serial No. 682,199.

To all whom it may concern:

Be it known that I, RALPH C. STIEFEL, a citizen of the United States, and a resident of Ellwood Cit in the county of Lawrence and State of g a new and useful Improvement in Tube and Smoothing Mills, of which the following is a specification.

This invention relates to-tube expanding and smoothing mills. The object is to provide a mill whereby tubes, particularly seamless tubes, can. be expeditiously and in a single operation increased in diameter, rounded, the walls reduced inthickness and smoothedboth inside and outside.

in the accompanying drawings Fig. 1 shows one form of mandrel and cooperating rolling bodies for attaining the object stated; and Figs. 2 and 3 illustrate modifications.

Diagonal or cross rolling mills for either piercing or expanding, on both, .lseamless tubes, are well known. Various forms and arrangements of rolling bodies for this purpose have heretofore been devised, and 221- so various forms of mandrels have been employed in conjunction therewith. Such mills, with the use of conical skew rolls,

or their equivalent. and in conjunction with a conical mandrel, have heretofore been.

proposed for expanding the tubes and reducing their Wall thickness. With such mills as heretofore constructed, great difficulty was experienced to performthis operation because the pressure required to get the necessary bite on the tubular blank to force it through the rolls and over the mandrelhas resulted in collapsing the tube or giving it such large ovality that itwill no longer rotate, and will :therefore stick in the rolls. Also with such mills it was experienced that if considerable wall reduction was efi'ected it resulted in producing helicoidal grooves or scores on the interior of the tube which were carried to some extent to its exterior. By means of the mill herein illustrated and now to be described these dificulties are avoided and a tube with smooth inside .and outside surfaces, of circular sha e, and of very much greater diameter an with much thinner walls than the originaltubular blank can be roduced.

n Fig. 1 the rolling bodies are indicated at 4: and 5. These are shown as of short conical form, but if desired they may be ennsylvania, have invented so-called disc rolls or any other suitable form. They are set with their axes at an angle, and askew, in order that in their rolling efi'ect they not only produce a rotary movement of the blank passing through the same, but also a forward feed thereof, in a well known manner. These rolling bodies for their major portions 6 are of such conical form and their angularity is such as to produce a pass which diverges quite rapidl towar s. the exit end of the pass. The forward portions 7 of the bodies are formed on a cone of greater angularity than their main body portions, giving a converging pass into which the tubular blank 8 is forced, by any suitable means such as by hand or an air or hydraulic pusher.

'Lying in the pass of these rolling bodies is the one piece mandrel, which as is common, is free to rotate on the endwise im-' movable mandrel bar 9. The tip of this mandrel has a cylindrical portion 10 of considerable length, lying forward of the diverging pass proper. lts forward end will either be round, as shown, or tapered. This c lindrical portion serves to support the tubular blank on its interior at the entrance end of thepass and preventsit from'collapsing and going oval to such an extent as to cause it to stick in the rolls.- To the rear'of this cylindrical tip portions is a conical portion 11, of an angularity' greater than the angularit of the adjacent plane of the pressure of the rolling bodies 4 and 5.

To the rear of the conical portion 11 is a second conical portion 12 which is of less angularity than the portion ll and of substantially the same angularity as that of the adjacent working faces of the rolling bodies 4 and 5 so that the pass at this ortion is of uniform dimensions. This portion of the pass serves to. remove from the tube walls any helicoidal grooves orand widely from the entrance end a I that is to say, the tube is rounded.

. pressure is put upon it, as is necessary in.

corrugations which may be formed in the preceding part of the pass and gives the tube smooth surfaces both inside and outside. Also the tube walls are trued or equalized, that is, rendered of uniform thickness all around, and the ovality is reduced,

sequently the tube leaving the rolls is smooth inside and outside, its walls are true, it is round its diameter is much greater than that or the entering blank, and the thickness of its wall is correspondingly reduced. 4

The length as well as the ratio of length of the two conical portions 11, and 12 can be varied according to the diameter of the tube to be manufactured and the degree of wall reduction which it is desired to obtain. The length of the conical portion 12 should be as great as possible, and greater than the length of the conical portion 11. The cylindrical tip 10 of the mandrel renders it impossible to so crush or collapse the tubular blank as to prevent it from jamming or sticking in the rolls, that is to say, it serves to retain the blank sufficiently near a cylindrical form to enable it to rotate, notwithstanding that very heavy order to start the blank to rotate and to feed it forward onto the conical portion ll of the mandrel.

In the form shown in Fig. 2 the mandrel has only a single conical portion 14, whose angularity is the same as that formed by the diverging portion of the adjacent working faces of the rolling bodies. In this form the reduction in wall thickness takes place on the cylindrical tip portion 10 of the mandrel and to some extent at the beginning of the single cone 14, but the rear portion of this cone serves to smooth the tube walls inside and outside, equalize their ghiclmess, and round the tube, as heretoore.

In both forms the mandrel is provided at its rear end with a cylindrical portion 15 which is generally provided with this type of mandrel.

The diameters of the rolling bodies increase in the same direction as the width or the pass increases and preferably in the same ratio in order to prevent twisting action on the blank.

The mill described enables a tubular blank to be rolled into a tube of much larger Conparatus as heretofore described. For instance, as shown in Fig. 3, there are two reducing cones 11 and 11, the latter being of less angularity than the former.

I claim:

1. In a tube expanding and smoothing mill, the combination with diagonal or skew rolling bodies disposed to form between them a pass the sides of which first converge and then diverge from the entrance end, of a one-piece mandrel located in said pass and having a substantially cylindrical forward portion serving to prevent collapse of the tubular blank under the grip of said rolling bodies as the tubular blank enters therebetween, and an adjacent conical portion increasing in diameter toward the exit end of the pass, the working frame of said mandrel and rolling bodies being so disposed that the walls of the blank at one portion of the pass are reduced in thickness and elongated peripherally and at another portion of the pass are equalized in thickness and the tube smoothed both inside and outside and rendered of circular form. V

2. In a tube expanding and smoothing mill, the combination with diagonal or skew rolling bodies disposed to form between them a pass the sides of which first converge and then diverge from the entrance end, of a one-piece mandrel located in said pass and having a substantially cylindrical tip portion serving to prevent collapse of the tubular blank under the grip of said rolling bodies as the blank enters the pass, an adjacent conical portion increasing in diameter toward the exit end of the pass and serving with said rolling bodies to reduce the wall thickness of the blank and to stretch the same peripherally, and a succeeding conical portion also of increasing diameter toward the exit end of the pass and serving to smooth the tube inside and outside, equalize its wall thickness and ten der it of circular form.

3. In a tube expanding and smoothing mill, the combination with diagonal or skew rolling bodies disposed to form between them a pass the sides of which first converge and then diverge from the entrance end, of a mandrel located in said pass and having a substantially cylindrical ti portion serving to prevent collapse of t e tubular blank under the grip of said rolling bodies as the blank enters the pass, a conical portion adjacent said cylindrical portion of greater angularity than the adjacent worki faces of the rolling bodies and Serving wit said rolling bodies to reduce the wall thickness of the blank and ex and it, and a succeeding conical portion 0 the same angularit as the adjacent workin faces of the rol ing bodies and-serving wit the said rolling bodies to smooth the tube walls inside and outside, equalize their thickness and render the tube circular.

4. In a tube expanding and smoothing mill, the combination with diagonal or skew rolling bodies, and a mandrel l g in the pass of said rolling bodies, said mandrel having a portion thereof disposed .at such In relation to the adjacent working 16 the same angularit as the adjacent work- 20 ing faces of the re ing bodies and servin therewith to render the tube circular, smooth the tube walls inside and outside, and equalize their thickness.

In testimony whereof, I sign m name. RALPH C. S EFEL.

Witnesa:

Enwm 0. Joanna. 

